Safety work light



@C 5 w54 D. G. MccoNNELL E'rAL 2,691,092

SAFETY WORK LIGHT Filed Dec. 30, 1950 'a' van'.

Anwen/5y Patented Oct. 5, 1954 SAFETY WORK LIGHT Donald G. McConnell and Richard A. Myers, Los Angeles, Calif., assignors to Douglas Aircraft Company, Inc., Santa Monica, Calif.

Application December 30, 1950, Seria-l No. 203,736

4 Claims.

This invention relates to lluorescent lights and provides a portable, generally improved light of this category which will be capable of substantially universal duty, serving as a regular component of a conventional overhead illuminating system, as a work light, an inspectors or closequarters light, or as a trouble-shooting light. In any oi" these cases, it may take the form either of a flood light or a spot light.

In attaining these and other ends hereinafter made apparent, the invention provides, among other things, a iluorescent lamp of such improved sliocl -absorbing construction that, if it is dropped, impacted, twisted or pulled, not even the fragile glass lighting element will be damaged nor will the electrical connections be loosened or otherwise impaired.

Since most injuries to fluorescent lamps are consequent upon the unauthorized tampering therewith of workers unversed in the details of fluorescent lamps, the invention concurrently provides a novel threadless tube and closure joining clamping configuration for hermetically sealing and locking the lighting element inside an indestructible transparent outer guard tube. The clamp and the clamped portions oi the tubes and their end closures can be separated or joined only by special tools normally unavailable to a workman using such light so that those not provided with this special tool will be unable to either assemble or disassemble the lamp.

The means for ballasting the electrical energy and starting the lamp located in a separate casing in the supply line to the lamp, is also attractive to tamperers or tinkerers. Accordingly, tamper-proof locking means and sealing means oi the same general type as the ones aforementioned are employed in conjunction with the starter casing and the electrical cord to similarly prevent injurious disassembly and inoperative assembly of the lamp.

Even those fluorescent lamps which have the lighting element resiliently mounted are unable to withstand tensions and torsions of large mag-- nitude, which are sometimes applied to the suspended lamp by workmens pulls and twists upon the cord. This invention enables the frangible fluorescent tube and the conductor wires leading to it to move longitudinally and rotatively independently of the outer or guard tube in which they are mounted, the latter absorbing the pulls and twists and the inner tube and wires remaining connected electrically with the lower mount. The upper end of the fluorescent tube and the wires are loatingly mounted in the upper end of the guard tube, thus relieving the frangible tube of destructive tension and torsion and concurrently facilitating the removal of an inoperative tube and the installation of a replacement tube.

It is a common complaint that the electrical connections in iluoroscent lamps between the light element and the mount and current conductors are not originally, or do not remain, of a degree of tightness and conductivity comparable to other electrical apparatus. Because of these loose, inadequate contacts most iluorescent lamps exhibit disproportionately high amounts of electrical resistance.

The present invention overcomes this and other defects by providing socket electrical terminals for the pair of terminal prongs on the iiuorescent tube, which are herein made resilient, and the sockets are vulcanized in the end closures in mutually laterally spaced relationship, this spacing being slightly different from the lateral spacing of the prongs. On establishment of the connection therefore, the resultant lateral spring load tends to maintain the prongs in much tighter contact with the sockets than is usually the case lin this art, whereby to lower the electrical resistance at these points.

The invention also provides a construction including a reflector inside the fluorescent lighting element configured and arranged for concentrating the light and substantially conning its emission to that side of the uorescent tube which is facing towards the working area, thus in elect intensifying the light in a preselected direction, and hence providing, as it were, a fluorescent spotlight.

Other advantages and accomplishments of the v invention will either become apparent or be made manifest as this description proceeds.

One of the presently preferred embodiments of these and other concepts. is illustrated merely by way ci further clarification and to enable reproduction of one of the many forms, in the accompanying drawings and described in detail herein after in conjunction therewith. However, it is to be understood that such illustration and description do not restrict the invention, which is dened and limited only by the subjoined claims.

In these drawings,

Figure 1 is an elevational view of the suspended lamp unit showing the lamp and control member in side elevation and the electrical supply line in fragmentary elevation;

Figure 2 is a fragmentary, longitudinal, sectional view of the lamp, showing the lighting elenient, electrical conductors member in elevation;

Figure 3 is a section on line 3-3 of Figure 2, iilustrating the spot-lighting construction of the lamp;

Figure 4 is a perspective, partly broken away, a lamp-controlling unit comprising a switch and a ballast transformer unit;

Figure 5 is a fragmentary view, partly in plan and partly in section, of a lamp-control unit in which the starter, instead of being disposed adjacent to or inside the lamp, is disposed in a casing adjacent to the ballast in place of the switch shown in Figure ll; and

Figure 6 is an expanded view, partly in fragmentary elevation and partly in section, showing a guard tube end-closure and lighting element support-plug provided with lateral spring load exerting socket terminals for reception of the resilient prong terminals on the fluorescent lighting element.

One of the presently preferred designs of the illuminating unit which incorporates the inventive features set forth above and many others, comprises, as shown in the accompanying drawings, an elongate fluorescent lighting element lll of sub-stantially the conventional construction and nature except as hereinafter mentioned in connection with specifically novel features of the invention. It includes a pair of metallic input terminals or prongs l I arranged at one end of the tube I) in the conventional manner and another pair of similar terminals I2 disposed at the opposite end of the glass lighting element.

rThe free ends of the sockets are laterally separated a distance, as shown in Figure 6, which is greater than the distance laterally separating the resilient, prong-like terminals I2 on the lighting element. Accordingly, when seated, these prongs are under a lateral spring-load which maintains tight contact and assures low electrical resistance thereat.

Adjacent to, and abutting the lower end of the lighting element IQ is a lower-end tube support and handle I3 of a yieldable, resilient nature and composed of an electrically non-conductive, thermally inert and chemically non-reactive material such as neoprene. A somewhat similar member E4, less elongate and more compact, is

and suspending provided at the upper end of the lighting element and is composed of the same material as the lower element. An outer tube I5 of transparent, nonconductive, elastically deformable material which is thermally and chemically inert and which, may be therefore composed of an organic, synthetic plastic such as one of the polyethylenes or Fiberglas, or Fiberglas and nylon, or Tulox (registered trade-mark of Extruded Plastics Company) is disposed substantially coaxially around the frangible lighting element and extends upwardly and downwardly beyond the adjacent ends of same.

In the usual manner, a conductor I6 in series at the outer end with the ballast and switch in the control unit leads to a glow coil of the conventional type, not shown but mounted in the lighting element at the upper end thereof, and thence to the starter, which may be mounted either in the tube adjacent thereto or in the control unit. Thence the electrical pressure is applied to the glow coil at the opposite end or the lighting element through a conductor Ita and thence through a conductor IED to the plug-end to the source of electrical energy. Mounted in the plug-end I3 is a pair of laterally spaced metallic 4 conductor sockets I'I vulcanized in the neoprene and staked at one end to the conductors IBa and IBb and terminating in ends I8, the inner ends of the sockets being surrounded by paper sleeves i9 for insulating purposes.

Similar terminal sockets 2| are disposed in laterally separated relationship in closure I3 subadjacent the other socket terminals and seat the terminals 23 of the conductors I6 and Ic.

The periphery of the support and closure member I4 at the upper end of the lamp is radially separated a distance 2li from the adjacent inner periphery of the guard tube I5 in order to allow the member I4 to slightly move longitudinally of the tube I5 and to slightly rotate therein, thereby to accommodate the expansion of the iiuorescent tube and to relieve the latter or its electrical contact prongs of torsion applied to the lamp or to tube I5. At the one side of this plug Ill is provided a longitudinally extending groove 25 providing an air clearance passageway for sreathing of the tube. Mounted coaxially of the member If are two laterally spaced metallic socket terminals for the fluorescent lighting element prongs I2, the upper ends of the sockets being anchored by beading to a Micarta anchorage disk 21 embedded in the neoprene. Paper sleeves or the like 23 are provided at the inner ends of the terminal sockets 2-5 for insulating purposes. Soldered connections 29 are provided between the ends of the bare conductor wires I6 and Ic and the electrical conductors leading thereto.

Mounted firmly inside the upper end of the guard tube I5 by a cylindrical portion a'butted at its inner face against the outer face of the support and closure member Ill is an end cap tting 3| composed of a yieldable, resilient, electrically non-conductive, thermally and chemically inert, organic, synthetic plastic such as neoprene or the like of a low Shore hardness. Coaxially mounted in the end cap is a suspension member 52 here taking the form of a re-curved hook or similar member of no greater lateral extent than the diameter of the outer tube and having its lower end mounted coaxially in the end cap, the lower end 33 being spheroidal and mounted in the end cap in a manner such as to permit universal movement of the lamp relative to the suspension points in all directions except the axial direction, that is, upwardly or downwardly.

A pair of metallic ferrules 34 is provided, one being disposed at each end of the lamp assembly. These ferrules are of the air hose type and are composed of a metallic material suinciently soft to be annularly inwardly crimpable by a special tool, such as a Schrader crimping or beading tool, yet are hard and rigid enough to be able to displace the polyethylene or similar material of the tube I5 radially inwardly into hermetic and locking engagement with the end cap 3i and the dual-nature handle and end closure I3. The annular crimp or beading en gagement 35 and 36 are not only formable only by means of a special tool such as the Schrader tool aforementioned, but can be ruptured or disengaged froni their engagements only by a special kind of tool such as a pair of diagonal pliers. Hence not only is it unfeasible for tamperers provided only with the ordinary electrician's tools, such as ordinary cutting pliers, to disassemble the lamp but, what is more important, it is impossible for them to reassemble a disassembled lamp without the aid of the special beading tool ,tov effectuatethe aforestated crimping.

Accordingly, the lamp is in effect tamper proof and is therefore immune to damage by tinkerers or other unauthorized and unskilled personnel unprovided with such tool.

The lighting element is not, contrary to the conventional practice, mounted coaxially of the tube I5 but is disposed eccentrically thereof, the eccentric disposition being achieved either by forming the end closures eccentrically or disposing the socket terminals off-center of the end closures. There is thus provided between the one portion of arc of the outer wall of the lighting element I and the adjacent inner portion of the wall of the guard tube I a radially and peripherally extending space A which is greater than the corresponding space at the diametrically opposite points of the tubes. The conductors I6 and I6c are disposed in the space A in parallelism to the tube I0 and are connected by a white or light colored neoprene covering having parallel opposite faces extending secantwise parallel to the diameters of the two tubes, the connecting web 38 thus providing a reflecting face disposed at right angles to the emission path of the light downwardly passing from the lighting element I0 and impinging thereon. This construction thus in effect concentrates the light emitted by the tube IIJ and directs it outwardly along the one diameter of the configuration of tubes instead of allowing the light from the lighting element to emit dispersedly all around the peripheries of the tubes. In effect therefore, the configuration provides a novel fluorescent spot lamp which directs the light where it is most needed, namely on the work to be illuminated.

The conductors leading out of the lamp are surrounded by a suitable rubber-like cord member 39 which is locally vulcanized to the material of the lower member I3 and relieves the conductors of tensile and other strains.

From the lower end of the lamp a four-conductor cord 4I extends into the switch or starter casing 42, which also includes electrical ballast means. The casing is formed at each end with a neck portion 42a surrounding the cord, a cord grip sleeve 43 being radially and longitudinally interposed between the neck and the cord and being vulcanized to the cord. Surrounding the cord grip sleeve and the necks of the casing at each end thereof is a metallic ferrule 44 similar to the ones employed to unite the components of the lamp itself and similarly beaded to the subadjacent components by means of an annular groove 45 therein and similarly forming annular beads 46 in the casing of the control group. l

Accordingly, the casing is hermetically sealed and locked to the sleeve and cord grip in a manner similar to that shown in Figure 2 and similarly provides a tamper proof connection of the parts which is disassemblable and assemblable only by means of an ordinarily unavailable special tool so that unauthorized personnel not provided with this tool will be unable to injure the inner components of the starter casing. Mounting brackets 4'I are provided inside the casing for supporting either the switch shown in Figure 4 or the starter in Figure 5.

In Figure 4 lamp control means for energizing and (ie-energizing the fluorescent lighting element are shown as comprising a conventional small switch 48 suitably mounted in the aforementioned brackets and an auto-transformer or ballast 49 which also serves as a choke. An energy input conductor 50 leads from the energy source through the ballast 49 and thence through the control casing without electrical connection to any other component therein and is connected at its leading end I6 to the input one of the terminals 26 on the upper end of the lighting element. Thereby the glow coil (not shown) in this end of the lighting element isjrendered incandescent. From the glow coil and the output one of the terminals 26, energy passes by way of conductor 5I to the upper pole 52 of the switch 48. With the switch button depressed and the switch closed, energy passes from the lower pole 53 of the switch Via conductor 54 to one of the lower terminals I I of the lighting element, thence through the glow coil (not shown) at this end and thence via conductor 55 (Figure 4) to the negative side of the energy source. The ballast 50 is grounded by means of a conductor 5l to the common ground 58 of the energy system.

In Figure 5, the switch of Figure 4 is replaced by a starter 58a mounted directly in the control casing, the energy source being suitably connected in series to the lamp, the ballast 59 and the starter by electrical conductors 60, 6I and 62. The lamp is lighted by merely inserting the plug 58 in the adjacent outlet of the electrical wiring system of the locality.

In order to prevent the breathing of the lamp from drawing thereinto circumambient gases which, in that particular locality, might be of an explosive or inflammable nature and ignitible by the occasional arcing at the electrical contacts of the lamp, an optically clear, chemically and thermally inert, electrically nonconductive liquid is inserted in the free space |50 between the two tubes. Preferably, this liquid is injected between the two tubes through one of the end closures, as by means of a syringe or the like. It is also preferable that such an amount of this liquid be injected as 'to substantially completely force out all the air initially occupying the space between the tubes and completely iill the space between the tubes. The liquid also aids the end closures in sealing the tubes.

Suitable such liquids include uid silicones, such as the colorless DC-ZOO silicone fluid of 25 centistokes viscosity at standard conditions of temperature and pressure. Another suitable such liquid is the water-white polybutene. Inspection of the liquid lled lamp can lbe accomplished at a glance because, if any liquid has been lost through leakage, the presence of air or combustible gas in space IDU will be immediately apparent and the lamp can then be serviced before being put into use.

The manner of functioning and use of the lamp unit are believed to be self evident and need not therefore be detailed herein. Suce it to say that the lamp can be suspended in the position shown in Figure l up off of the working area out of the way of the workman and can in this suspended position be angularly adjusted in the horizontal plane, in the lateral plane, and to a slight extent in the vertical plane to absorb displacements applied thereto by the workman or to enable adjustment of the lamp to better illuminate the working area.

It will be noted that the outer casing or guard tube and the upper closure are adjustable independently of the lighting element, being movable longitudinally and rotatably as a unit to absorb pulls or twists applied to the outer casing without damage to the lighting element or its mounting.

We claim:

1. A safety fluorescent work lamp, comprising:

a guard tube open at each of its ends, said tube being composed of an elastic transparent plastic material; a tube closure-member of resilient material mounted in each of the ends of said tube; a iiuorescent lighting element disposed longitudinally in said guard tube and mounted independently of said tube; means for electrically connecting said element to an energy-source so as to effect illumination of said element; a discrete, separate permanently-distortable ferrule disposed around each end of said guard-tube, each of said ferrules having an annular flange engaging the outer face of the adjacent tubeclosure member so as to anchor said member against axial thrusts thereon, and each of said ferrules including an annular, permanently-set indentation intermediate its ends, said indentation extending radially inwardly into locking engagement with the guard tube and displacing the wall of said tube inwardly and hermetically against the adjacent resilient closure member, both the indentation in the ferrule and the annular displacement in the elastic guard tube being formable and disengageable only by a special tool normally unavailable to work-lamp using personnel whereby to prevent unauthorized disassembly of said lamp.

2. In a safety fluorescent work lamp; a guard tube having a substantially soft and yieldable tube end-closure member of resilient, rubber-like material xedly mounted in the one end thereof; electrical conductors anchored at one end in said tube and extending outwardly of the opposite end of said tube; and a lamp-support engaging member disposed at the rst-said end or said tube and having an enlarged inner end swivelly socketed in said end-closure member, the portion of said closure-member that lies outwardly adjacent the inner end of said support-engaging member being outwardly yieldable under a predetermined tension applied longitudinally of said lamp so as to enable the lamp to come free of the support under accidental tensile loads applied to said conductors, thereby to relieve said lamp of said loads.

3. In a safety fluorescent Work lamp: a guard tube; resilient means closing same at each of its ends; a fluorescent lighting element disposed longitudinally in said guard tube and directly anchored at its one end in the adjacent resilient tube-closing means so as to constitute a resilient support of said lighting element; means for electrically connecting said element to an energysource so as to eiect illumination of said element, said means including electrical connections to the opposite ends of said lighting-element; and a substantially free-floating lighting element anchorage-member comprising a block of substantially cylindrical, resilient, rubber-like material disposed at the opposite end of said tube and having at least a portion of its periphery radially spaced from said tube and lying coaxially longitudinally inwardly of the adjacent tubeclosing means, said iioating anchorage-member being adapted to remain stationary with respect to rotative and longitudinal movements of the closed gua-rd tube, thereby to hold said lighting element stationary and relieve same and said conductors of torsions and. tensions applied to said guard tube so as to maintain said light element and the conductor connections thereto intact under said torsione and tensions.

4. A safety iiuorescent Work lamp, comprising: an electrically non-conductive guard-tube; a iiuorescent lighting-element disposed longitudinally in said tube; rst and second electrically non-conductive means for anchoring said element, said means being disposed transversely in said guard tube at the respective ends thereof; iirst and second electrical conductor means for energizing said lighting element, both said conductor means extending through the rst one of said anchoring means, the first conductor means extending longitudinally inside said tube from the iirst anchoring means to the second anchoring means and into shielded contact inside said second anchoring means with the distal end of said lighting element, the second of said conductor means extending through the rst said anchoring means into shielded contact inside said first anchoring means with the proximal end o said lighting element; resilient plug means disposed coaxially in the end of said guard tube adjacent said second anchoring means; and an annular ferrule lockingly engaged with the periphery of said guard tube at each end thereof, said ferrule having a portion annularly displaced inwardly into said guard tube suiiiciently to displace said tube into the adjacent rst anchoring means and plug means so as to integrate the tube, plug means, and anchoring means into a unitary casing of a type in which all currentcarrying parts are permanently segregated from contact by lamp-users and which is disintegratable to provide access to the lighting element only by special tools normally unavailable to lampusers.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 562,208 Waegel June 16, 1896 1,794,777 Kliegl Mar. 3, 1931 2,347,174 Cross et al. Apr. 25, 1944 2,857,591 Kleinfelder Sept. 5, 1944 2,429,859 Stephens Oct. 28, 1947 2,439,589 Sundell Apr. 13, 1948 2,447,922 Tuck Aug. 24, 1948 2,472,180 Tittle June 7, 1949 FOREIGN PATENTS Number Country Date 525,325 Germany May 22, 1931 

